We also offer Molecular Probes® N-(t-BOC)-Aminooxyacetic Acid, Tetrafluorophenyl Ester, which is an amine-reactive protected hydroxylamine that is useful for synthesizing new aldehyde- and ketone-reactive probes in an organic solvent. Following coupling to aliphatic amines, the t-BOC group can be quantitatively removed with trifluoroacetic acid.